The present invention is directed to an air filtration media and, in particular, to a single layer, non-woven air filtration media comprising a blanket of randomly oriented and randomly intermingled polymeric microfibers, staple fibers and bonding fibers.
Heating, ventilating and air conditioning systems used in commercial and industrial buildings are provided with air filtration units to clean the air being circulated throughout the buildings. These air filtration units typically employ a sock type of filter with about six separate pockets, all of which are open at the upstream end and closed at the downstream end, to filter dirt particles from the air flowing through the heating, ventilating and air conditioning systems. The filter media presently used in these sock filters comprises a laminate of different fibrous blankets which each have different average fiber diameters and different functions. Frequently, one layer functions to remove coarse dirt particles from the air stream, a second layer functions to remove fine dirt particles from the air stream; and a third layer functions mainly as a supporting or backing layer.
These sock filters work satisfactorily. However, since two or more separate fibrous blankets must be combined into a single laminate of two or more layers prior to forming the sock filters, the sock filters presently in use are relatively expensive to fabricate. By eliminating the need to form the filter media used in the sock filters from a laminate of several different fibrous blankets, the costs and labor involved in producing the sock filters can be reduced. In addition, the filter manufacturer must now bear the expense of maintaining a relatively large inventory of different filter media blankets from which to fabricate sock filters meeting various operating or service requirements. Thus, there has been a need to provide a simpler, efficient filter media to reduce the filter manufacturer's labor requirements, fabrication costs and inventory requirements.